Direction: Fill in the blanks with suitable position words. 
The birds are flying _____________ the hills.

The correct answer is: Over

The prepositions given in the options are 'under' and 'over'. 'The birds are flying under the hills' would mean that the birds are flying below the hills, which is wrong. 'The birds are flying over the hills' would mean that the birds are flying just above the hills, which is correct. Hence, the answer is OVER.